Southbend Essential Guide to Backlash Adjustment on a Lathe: Tools, Techniques, and What is Backlash

	S E R V I C E
13" Heavy 13® Gearhead Lathe		For Machines Mfg. Since 5/11

Backlash Adjustment

Backlash is the amount of free play felt while changing rotation directions with the handwheel. This can be adjusted on the compound rest

and cross slide leadscrews. Before beginning any adjustment, make sure that all associated components have been cleaned and lubricated.

Reducing backlash to less than 0.002" is impractical and can lead to accelerated wear of the wedge, nut, and leadscrew. Avoid the temptation to overtighten the backlash set screw while adjusting.

Compound Rest
Tools Needed:	Qty
Hex Wrench 3mm	1

The compound rest backlash is adjusted by tightening the set screws shown in Figure 113. When these screws are adjusted against the leadscrew nut, they offset part of the nut to remove play between the nut and leadscrew.

Set Screws

Figure 113. Compound rest backlash adjustment set

screws.

To adjust the backlash, rock the handwheel back and forth, and tighten the screws slowly until the backlash is approximately 0.002"–0.003", as indicated on the graduated dial.

If you end up adjusting the nut too tight, loosen the set screws, tap the compound rest a few times with a rubber or wooden mallet, and turn the handwheel slowly back and forth until it moves freely—then try again.

Cross Slide
Tools Needed:	Qty
Hex Wrench 3mm	................................................. 1
Hex Wrench 5mm	................................................ 1

The cross slide backlash is adjusted by loosening all four cap screws shown in Figure 114, then tightening the center set screw. This will push down on a wedge and force the leadscrew nut apart, taking up lash between the nut and leadscrew.

Cap Screws

Set

Screw

Figure 114. Cross slide backlash adjustment screws.

To adjust the backlash, remove the compound rest and loosen the four cap screws. Then, rock the cross slide handwheel back and forth, and tighten the set screw slowly until the backlash is at approximately 0.002"–0.003" as indicated on the graduated dial.

If you end up adjusting the nut too tight, loosen the set screw, tap the cross slide a few times with a rubber or wooden mallet, and turn the handwheel slowly back and forth, until the handle turns freely—then try again.

Remember to re-tighten the four cap screws when you are finished.

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